Trevor: I just posted
build 1330 with max-threads of 16. Give it a try!
AlecJames: Backgrounds of all kinds (Panorama, Image and Cube Map) should work for all camera views in all renderers in build 1330.
selden: the int Attribute MaxThreads sets the maximum number of threads. So if you have a 4 code CPU you can set it to 3 to leave a core for you to use while it's rendering. Alternately, you can set it to -1 to use all but one thread, or -2, etc.
Raxx: the main difference with the multi-threaded Fast AA for your scene is the way Anim8or handles soft shadows.
Previously Anim8or would sample sqrt(n) samples for n sample anti aliasing and see what the max color difference was between the samples. If it was too large, Anima8or would take another sqrt(n) samples. Then if the color still wasn't converging fast enough it would sample the full number.
Now the color difference isn't used because highly varying textures could cause a slowdown. Instead Anim8or uses a mask of what lights are visible for each sample. If it is different for the first sqrt(n) samples, then Anim8or samples all the rest. This works very well for normal shadow edges and soft shadow edges that aren't "too soft", i.e. the number of pixels that are partially shadowed is small. You scene has several soft shadowed lights that are very close to the objects which means a lot of pixels are softly lit. So Anim8or sample all samples for them. Since you are using 100 sample FastAA this adds a lot of time.
I have a more sophisticated algorithm that I want to try for later builds that should make much smoother soft shadows with fewer samples. It involves filtering the light separately from the surface material. I don't know when I'll have it ready so keep you fingers crossed!